An oil refinery or petroleum refinery is an industrial process plant where petroleum (crude oil) is transformed and refined into products such as gasoline (petrol), diesel fuel, asphalt base, fuel oils, heating oil, kerosene, liquefied petroleum gas and petroleum naphtha.^[1][2][3] Petrochemical feedstock like ethylene and propylene can also be produced directly by cracking crude oil without the need of using refined products of crude oil such as naphtha.^[4][5] The crude oil feedstock has typically been processed by an oil production plant. There is usually an oil depot at or near an oil refinery for the storage of incoming crude oil feedstock as well as bulk liquid products. In 2020, the total capacity of global refineries for crude oil was about 101.2 million barrels per day.^[6]

Oil refineries are typically large, sprawling industrial complexes with extensive piping running throughout, carrying streams of fluids between large chemical processing units, such as distillation columns. In many ways, oil refineries use many different technologies and can be thought of as types of chemical plants. Since December 2008, the world's largest oil refinery has been the Jamnagar Refinery owned by Reliance Industries, located in Gujarat, India, with a processing capacity of 1.24 million barrels (197,000 m³) per day.

Oil refineries are an essential part of the petroleum industry's downstream sector.^[7]

Anacortes Refinery, on the north end of March Point southeast of Anacortes, Washington, United States

Grangemouth Refinery, in Scotland

Jamnagar Refinery, the world's largest oil refinery, in Gujarat, India

Oil refinery in Brod, Republika Srpska

History

The Chinese were among the first civilizations to refine oil.^[8] As early as the first century, the Chinese were refining crude oil for use as an energy source.^[9][8] Between 512 and 518, in the late Northern Wei dynasty, the Chinese geographer, writer and politician Li Daoyuan introduced the process of refining oil into various lubricants in his famous work Commentary on the Water Classic.^[10][9][8]

Crude oil was often distilled by Persian chemists, with clear descriptions given in handbooks such as those of Muhammad ibn Zakarīya Rāzi (c. 865–925).^[11] The streets of Baghdad were paved with tar, derived from petroleum that became accessible from natural fields in the region. In the 9th century, oil fields were exploited in the area around modern Baku, Azerbaijan. These fields were described by the Arab geographer Abu al-Hasan 'Alī al-Mas'ūdī in the 10th century, and by Marco Polo in the 13th century, who described the output of those wells as hundreds of shiploads.^[12] Arab and Persian chemists also distilled crude oil in order to produce flammable products for military purposes. Through Islamic Spain, distillation became available in Western Europe by the 12th century.^[13]

In the Northern Song dynasty (960–1127), a workshop called the "Fierce Oil Workshop", was established in the city of Kaifeng to produce refined oil for the Song military as a weapon. The troops would then fill iron cans with refined oil and throw them toward the enemy troops, causing a fire – effectively the world's first "fire bomb". The workshop was one of the world's earliest oil refining factories where thousands of people worked to produce Chinese oil-powered weaponry.^[14]

Prior to the nineteenth century, petroleum was known and utilized in various fashions in Babylon, Egypt, China, Philippines, Rome and Azerbaijan. However, the modern history of the petroleum industry is said to have begun in 1846 when Abraham Gesner of Nova Scotia, Canada devised a process to produce kerosene from coal. Shortly thereafter, in 1854, Ignacy Łukasiewicz began producing kerosene from hand-dug oil wells near the town of Krosno, Poland.^{[citation needed]}

Romania was registered as the first country in world oil production statistics, according to the Academy Of World Records.^[15][16]

In North America, the first oil well was drilled in 1858 by James Miller Williams in Oil Springs, Ontario, Canada.^[17] In the United States, the petroleum industry began in 1859 when Edwin Drake found oil near Titusville, Pennsylvania.^[18] The industry grew slowly in the 1800s, primarily producing kerosene for oil lamps. In the early twentieth century, the introduction of the internal combustion engine and its use in automobiles created a market for gasoline that was the impetus for fairly rapid growth of the petroleum industry. The early finds of petroleum like those in Ontario and Pennsylvania were soon outstripped by large oil "booms" in Oklahoma, Texas and California.^[19]

Samuel Kier established America's first oil refinery in Pittsburgh on Seventh Avenue near Grant Street, in 1853.^[20] Polish pharmacist and inventor Ignacy Łukasiewicz established an oil refinery in Jasło, then part of the Austro-Hungarian Empire (now in Poland) in 1854.^{[citation needed]}

The first large refinery opened at Ploiești, Romania, in 1856–1857.^[15] It was in Ploiesti that, 51 years later, in 1908, Lazăr Edeleanu, a Romanian chemist of Jewish origin who got his PhD in 1887 by discovering amphetamine, invented, patented and tested on industrial scale the first modern method of liquid extraction for refining crude oil, the Edeleanu process. This increased the refining efficiency compared to pure fractional distillation and allowed a massive development of the refining plants. Successively, the process was implemented in France, Germany, U.S. and in a few decades became worldwide spread. In 1910 Edeleanu founded "Allgemeine Gesellschaft für Chemische Industrie" in Germany, which, given the success of the name, changed to Edeleanu GmbH, in 1930. During the time of Nazi rule, the company was bought by the Deutsche Erdöl-AG and Edeleanu, being of Jewish origin, moved back to Romania. After the war, the trademark was used by the successor company EDELEANU Gesellschaft mbH Alzenau (RWE) for many petroleum products, while the company was lately integrated as EDL in the Pörner Group. The Ploiești refineries, after being taken over by Nazi Germany, were bombed in the 1943 Operation Tidal Wave by the Allies, during the Oil Campaign of World War II.^{[citation needed]}

Another close contender for the title of hosting the world's oldest oil refinery is Salzbergen in Lower Saxony, Germany. Salzbergen's refinery was opened in 1860.^{[citation needed]}

At one point, the refinery in Ras Tanura, Saudi Arabia owned by Saudi Aramco was claimed to be the largest oil refinery in the world. For most of the 20th century, the largest refinery was the Abadan Refinery in Iran. This refinery suffered extensive damage during the Iran–Iraq War. Since 25 December 2008, the world's largest refinery complex is the Jamnagar Refinery Complex, consisting of two refineries side by side operated by Reliance Industries Limited in Jamnagar, India with a combined production capacity of 1,240,000 barrels per day (197,000 m³/d).^{[citation needed]}

Prior to World War II in the early 1940s, most petroleum refineries in the United States consisted simply of crude oil distillation units (often referred to as atmospheric crude oil distillation units). Some refineries also had vacuum distillation units as well as thermal cracking units such as visbreakers (viscosity breakers, units to lower the viscosity of the oil). All of the many other refining processes discussed below were developed during the war or within a few years after the war. They became commercially available within 5 to 10 years after the war ended and the worldwide petroleum industry experienced very rapid growth. The driving force for that growth in technology and in the number and size of refineries worldwide was the growing demand for automotive gasoline and aircraft fuel.^{[citation needed]}

In the United States, for various complex economic and political reasons, the construction of new refineries came to a virtual stop in about the 1980s. However, many of the existing refineries in the United States have revamped many of their units and/or constructed add-on units in order to: increase their crude oil processing capacity, increase the octane rating of their product gasoline, lower the sulfur content of their diesel fuel and home heating fuels to comply with environmental regulations and comply with environmental air pollution and water pollution requirements.

United States

Main article: Petroleum refining in the United States

In the 19th century, refineries in the U.S. processed crude oil primarily to recover the kerosene. There was no market for the more volatile fraction, including gasoline, which was considered waste and was often dumped directly into the nearest river. The invention of the automobile shifted demand to gasoline and diesel, which remain the primary refined products today.^[22]

Today, national and state legislation require refineries to meet stringent air and water cleanliness standards. In fact, oil companies in the U.S. perceive obtaining a permit to build a modern refinery to be so difficult and costly that no new refineries were built (though many have been expanded) in the U.S. from 1976 until 2014 when the small Dakota Prairie Refinery in North Dakota began operation.^[23] More than half the refineries that existed in 1981 are now closed due to low utilization rates and accelerating mergers.^[24] As a result of these closures total US refinery capacity fell between 1981 and 1995, though the operating capacity stayed fairly constant in that time period at around 15,000,000 barrels per day (2,400,000 m³/d).^[25] Increases in facility size and improvements in efficiencies have offset much of the lost physical capacity of the industry. In 1982 (the earliest data provided), the United States operated 301 refineries with a combined capacity of 17.9 million barrels (2,850,000 m³) of crude oil each calendar day. In 2010, there were 149 operable U.S. refineries with a combined capacity of 17.6 million barrels (2,800,000 m³) per calendar day.^[26] By 2014 the number of refineries had decreased to 140 but the total capacity increased to 18.02 million barrels (2,865,000 m³) per calendar day. To reduce operating costs and depreciation, refining is operated in fewer sites but of bigger capacity.^{[citation needed]}

In 2009 through 2010, as revenue streams in the oil business dried up and profitability of oil refineries fell due to lower demand for product and high reserves of supply preceding the economic recession, oil companies began to close or sell the less profitable refineries.^[27]

Operation

Neste Oil refinery in Porvoo, Finland

The oil refinery in Haifa, Israel, is capable of processing about 9 million tons (66 million barrels) of crude oil a year. Its two cooling towers are landmarks of the city's skyline.

Raw or unprocessed crude oil is not generally useful in industrial applications, although "light, sweet" (low viscosity, low sulfur) crude oil has been used directly as a burner fuel to produce steam for the propulsion of seagoing vessels.^{[citation needed]} The lighter elements, however, form explosive vapors in the fuel tanks and are therefore hazardous, especially in warships.^{[citation needed]}

The hundreds of different hydrocarbon molecules in crude oil are separated in a refinery into components that can be used as fuels, lubricants, and feedstocks in petrochemical processes that manufacture such products as plastics, detergents, solvents, elastomers, and fibers such as nylon and polyesters.

Petroleum fossil fuels are burned in internal combustion engines to provide power for ships, automobiles, aircraft engines, lawn mowers, dirt bikes, and other machines. Different boiling points allow the hydrocarbons to be separated by distillation. Since the lighter liquid products are in great demand for use in internal combustion engines, a modern refinery will convert heavy hydrocarbons and lighter gaseous elements into these higher-value products.^[28]

Oil can be used in a variety of ways because it contains hydrocarbons of varying molecular masses, forms and lengths such as paraffins, aromatics, naphthenes (or cycloalkanes), alkenes, dienes, and alkynes.^[29] While the molecules in crude oil include different atoms such as sulfur and nitrogen, the hydrocarbons are the most common form of molecules, which are molecules of varying lengths and complexity made of hydrogen and carbon atoms, and a small number of oxygen atoms. The differences in the structure of these molecules account for their varying physical and chemical properties, and it is this variety that makes crude oil useful in a broad range of several applications.

Once separated and purified of any contaminants and impurities, the fuel or lubricant can be sold without further processing. Smaller molecules such as isobutane and propylene or butylenes can be recombined to meet specific octane requirements by processes such as alkylation, or more commonly, dimerization. The octane grade of gasoline can also be improved by catalytic reforming, which involves removing hydrogen from hydrocarbons producing compounds with higher octane ratings such as aromatics. Intermediate products such as gasoils can even be reprocessed to break a heavy, long-chained oil into a lighter short-chained one, by various forms of cracking such as fluid catalytic cracking, thermal cracking, and hydrocracking. The final step in gasoline production is the blending of fuels with different octane ratings, vapor pressures, and other properties to meet product specifications. Another method for reprocessing and upgrading these intermediate products (residual oils) uses a devolatilization process to separate usable oil from the waste asphaltene material. Certain cracked streams are particularly suitable to produce petrochemicals includes polypropylene, heavier polymers, and block polymers based on the molecular weight and the characteristics of the olefin specie that is cracked from the source feedstock.^[30]

Oil refineries are large-scale plants, processing about a hundred thousand to several hundred thousand barrels of crude oil a day. Because of the high capacity, many of the units operate continuously, as opposed to processing in batches, at steady state or nearly steady state for months to years. The high capacity also makes process optimization and advanced process control very desirable.^{[citation needed]}

Major products

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Petroleum products are materials derived from crude oil (petroleum) as it is processed in oil refineries. The majority of petroleum is converted to petroleum products, which includes several classes of fuels.^[32]

Oil refineries also produce various intermediate products such as hydrogen, light hydrocarbons, reformate and pyrolysis gasoline. These are not usually transported but instead are blended or processed further on-site. Chemical plants are thus often adjacent to oil refineries or a number of further chemical processes are integrated into it. For example, light hydrocarbons are steam-cracked in an ethylene plant, and the produced ethylene is polymerized to produce polyethene.^{[citation needed]}

To ensure both proper separation and environmental protection, a very low sulfur content is necessary in all but the heaviest products. The crude sulfur contaminant is transformed to hydrogen sulfide via catalytic hydrodesulfurization and removed from the product stream via amine gas treating. Using the Claus process, hydrogen sulfide is afterward transformed to elementary sulfur to be sold to the chemical industry. The rather large heat energy freed by this process is directly used in the other parts of the refinery. Often an electrical power plant is combined into the whole refinery process to take up the excess heat.

According to the composition of the crude oil and depending on the demands of the market, refineries can produce different shares of petroleum products. The largest share of oil products is used as "energy carriers", i.e. various grades of fuel oil and gasoline. These fuels include or can be blended to give gasoline, jet fuel, diesel fuel, heating oil, and heavier fuel oils. Heavier (less volatile) fractions can also be used to produce asphalt, tar, paraffin wax, lubricating and other heavy oils. Refineries also produce other chemicals, some of which are used in chemical processes to produce plastics and other useful materials. Since petroleum often contains a few percent sulfur-containing molecules, elemental sulfur is also often produced as a petroleum product. Carbon, in the form of petroleum coke, and hydrogen may also be produced as petroleum products. The hydrogen produced is often used as an intermediate product for other oil refinery processes such as hydrocracking and hydrodesulfurization.^[33]

Chemical processes

Flow diagram of typical refinery

The image below is a schematic flow diagram of a typical oil refinery that depicts the various unit processes and the flow of intermediate product streams that occurs between the inlet crude oil feedstock and the final end products. The diagram depicts only one of the literally hundreds of different oil refinery configurations. The diagram also does not include any of the usual refinery facilities providing utilities such as steam, cooling water, and electric power as well as storage tanks for crude oil feedstock and for intermediate products and end products.^{[1][107][108][109]}

• 

Schematic flow diagram of a typical oil refinery

There are many process configurations other than that depicted above. For example, the vacuum distillation unit may also produce fractions that can be refined into end products such as spindle oil used in the textile industry, light machine oil, motor oil, and various waxes.

Crude oil distillation unit

The crude oil distillation unit (CDU) is the first processing unit in virtually all petroleum refineries. The CDU distills the incoming crude oil into various fractions of different boiling ranges, each of which is then processed further in the other refinery processing units. The CDU is often referred to as the atmospheric distillation unit because it operates at slightly above atmospheric pressure.^[1][2][69] Below is a schematic flow diagram of a typical crude oil distillation unit. The incoming crude oil is preheated by exchanging heat with some of the hot, distilled fractions and other streams. It is then desalted to remove inorganic salts (primarily sodium chloride).

Following the desalter, the crude oil is further heated by exchanging heat with some of the hot, distilled fractions and other streams. It is then heated in a fuel-fired furnace (fired heater) to a temperature of about 398 °C and routed into the bottom of the distillation unit.

The cooling and condensing of the distillation tower overhead is provided partially by exchanging heat with the incoming crude oil and partially by either an air-cooled or water-cooled condenser. Additional heat is removed from the distillation column by a pumparound system as shown in the diagram below.

As shown in the flow diagram, the overhead distillate fraction from the distillation column is naphtha. The fractions removed from the side of the distillation column at various points between the column top and bottom are called sidecuts. Each of the sidecuts (i.e., the kerosene, light gas oil, and heavy gas oil) is cooled by exchanging heat with the incoming crude oil. All of the fractions (i.e., the overhead naphtha, the sidecuts, and the bottom residue) are sent to intermediate storage tanks before being processed further.

Location of refineries

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A party searching for a site to construct a refinery or a chemical plant needs to consider the following issues:

• The site has to be reasonably far from residential areas.
• Infrastructure should be available for the supply of raw materials and shipment of products to markets.
• Energy to operate the plant should be available.
• Facilities should be available for waste disposal.

Factors affecting site selection for oil refinery:

• Availability of land
• Conditions of traffic and transportation
• Conditions of utilities – power supply, water supply
• Availability of labours and resources

Refineries that use a large amount of steam and cooling water need to have an abundant source of water. Oil refineries, therefore, are often located nearby navigable rivers or on a seashore, nearby a port. Such location also gives access to transportation by river or by sea. The advantages of transporting crude oil by pipeline are evident, and oil companies often transport a large volume of fuel to distribution terminals by pipeline. A pipeline may not be practical for products with small output, and railcars, road tankers, and barges are used.

Petrochemical plants and solvent manufacturing (fine fractionating) plants need spaces for further processing of a large volume of refinery products, or to mix chemical additives with a product at source rather than at blending terminals.

Safety and environment

The refining process releases a number of different chemicals into the atmosphere (see AP 42 Compilation of Air Pollutant Emission Factors) and a notable odor normally accompanies the presence of a refinery. Aside from air pollution impacts there are also wastewater concerns,^[106] risks of industrial accidents such as fire and explosion, and noise health effects due to industrial noise.^[110]

Many governments worldwide have mandated restrictions on contaminants that refineries release, and most refineries have installed the equipment needed to comply with the requirements of the pertinent environmental protection regulatory agencies. In the United States, there is strong pressure to prevent the development of new refineries, and no major refinery has been built in the country since Marathon's Garyville, Louisiana facility in 1976. However, many existing refineries have been expanded during that time. Environmental restrictions and pressure to prevent the construction of new refineries may have also contributed to rising fuel prices in the United States.^[111] Additionally, many refineries (more than 100 since the 1980s) have closed due to obsolescence and/or merger activity within the industry itself.^[112]

Environmental and safety concerns mean that oil refineries are sometimes located some distance away from major urban areas. Nevertheless, there are many instances where refinery operations are close to populated areas and pose health risks.^[113][114] In California's Contra Costa County and Solano County, a shoreline necklace of refineries, built in the early 20th century before this area was populated, and associated chemical plants are adjacent to urban areas in Richmond, Martinez, Pacheco, Concord, Pittsburg, Vallejo and Benicia, with occasional accidental events that require "shelter in place" orders to the adjacent populations. A number of refineries are located in Sherwood Park, Alberta, directly adjacent to the City of Edmonton, which has a population of over 1,000,000 residents.^[115]

NIOSH criteria for occupational exposure to refined petroleum solvents have been available since 1977.^[116]

Worker health

Corrosion

Corrosion of metallic components is a major factor of inefficiency in the refining process. Because it leads to equipment failure, it is a primary driver for the refinery maintenance schedule. Corrosion-related direct costs in the U.S. petroleum industry as of 1996 were estimated at US$3.7 billion.^[172][179]

Corrosion occurs in various forms in the refining process, such as pitting corrosion from water droplets, embrittlement from hydrogen, and stress corrosion cracking from sulfide attack.^[180] From a materials standpoint, carbon steel is used for upwards of 80 percent of refinery components, which is beneficial due to its low cost. Carbon steel is resistant to the most common forms of corrosion, particularly from hydrocarbon impurities at temperatures below 205 °C, but other corrosive chemicals and environments prevent its use everywhere. Common replacement materials are low alloy steels containing chromium and molybdenum, with stainless steels containing more chromium dealing with more corrosive environments. More expensive materials commonly used are nickel, titanium, and copper alloys. These are primarily saved for the most problematic areas where extremely high temperatures and/or very corrosive chemicals are present.^[181]

Corrosion is fought by a complex system of monitoring, preventative repairs, and careful use of materials. Monitoring methods include both offline checks taken during maintenance and online monitoring. Offline checks measure corrosion after it has occurred, telling the engineer when equipment must be replaced based on the historical information they have collected. This is referred to as preventative management.

Online systems are a more modern development and are revolutionizing the way corrosion is approached. There are several types of online corrosion monitoring technologies such as linear polarization resistance, electrochemical noise and electrical resistance. Online monitoring has generally had slow reporting rates in the past (minutes or hours) and been limited by process conditions and sources of error but newer technologies can report rates up to twice per minute with much higher accuracy (referred to as real-time monitoring). This allows process engineers to treat corrosion as another process variable that can be optimized in the system. Immediate responses to process changes allow the control of corrosion mechanisms, so they can be minimized while also maximizing production output.^[171] In an ideal situation having on-line corrosion information that is accurate and real-time will allow conditions that cause high corrosion rates to be identified and reduced. This is known as predictive management.

Materials methods include selecting the proper material for the application. In areas of minimal corrosion, cheap materials are preferable, but when bad corrosion can occur, more expensive but longer-lasting materials should be used. Other materials methods come in the form of protective barriers between corrosive substances and the equipment metals. These can be either a lining of refractory material such as standard Portland cement or other special acid-resistant cement that is shot onto the inner surface of the vessel. Also available are thin overlays of more expensive metals that protect cheaper metal against corrosion without requiring much material.^[182]

See also

• Acid gas – Gas with acidic pH
• AP 42 Compilation of Air Pollutant Emission Factors
• API oil-water separator – Industrial wastewater processing devicePages displaying short descriptions of redirect targets
• Biorefinery – Refinery that converts biomass to energy and other beneficial byproducts
• Ethanol fuel – Type of biofuel
• Butanol fuel – Fuel for internal combustion engines
• Gas flare – Safety device for burning off flammable gas
• H-Bio – Diesel‑refining with vegetable oil
• Industrial wastewater treatment – Processes for treating wastewater produced as an industrial by-product
• K factor crude oil refining
• List of oil refineries
• Natural-gas processing – Industrial processes designed to purify raw natural gas
• Nelson complexity index – Conversion calculation in petroluem refinery
• Sour gas – Term for gas with significant amounts of hydrogen sulfide
• Atmospheric distillation of crude oil – Atmospheric-pressure oil separation process
• List of countries by oil production

References

Bibliography

• Deng, Yinke; Wang, Pinxing (2011). Ancient Chinese Inventions. Cambridge University Press. ISBN 978-0-521-18692-6. OCLC 671710733.

External links

• Interactive map of UK refineries
• Searchable United States Refinery Map Archived April 28, 2009, at the Wayback Machine
• Complete, detailed refinery description
• Ecomuseum Bergslagen – history of Oljeön, Sweden
• Fueling Profits: Report on Industry Consolidation (publication of the Consumer Federation of America)
• Price Spikes, Excess Profits and Excuses (publication of the Consumer Federation of America)
• 2022 AFPM Refinery Listing (free) with Detailed Unit Information (note the data is collected annually by the US Dept. of Energy)
• National Occupational Research Agenda Oil and gas Extraction Council